阅读说明：本技术 一种用于重金属检测的铋膜修饰电极及其制备方法 (Bismuth film modified electrode for heavy metal detection and preparation method thereof ) 是由 奚亚男 胡保帅 崔皓博 于 2021-08-05 设计创作，主要内容包括：本发明提供了一种用于重金属检测的铋膜修饰电极及其制备方法,具体采用电化学沉积的方法,在电极基底表面原位修饰铋膜,将制得的铋膜修饰电极作为工作电极,并将工作电极、参比电极与辅助电极共面化,实现了电极间距为1～100μm的微型化设计,大大降低了溶液电阻,提高了检测的响应性,并将其应用于重金属检测,还可在铋膜表面修饰海藻酸胶膜,进一步提升电极性能,实现了快速简便检测重金属的目的,为高可靠性的微型传感器的设计与应用提供了新思路。(The invention provides a bismuth film modified electrode for heavy metal detection and a preparation method thereof, and particularly relates to a bismuth film modified electrode for heavy metal detection and a preparation method thereof, wherein an electrochemical deposition method is adopted, a bismuth film is modified on the surface of an electrode substrate in situ, the prepared bismuth film modified electrode is used as a working electrode, and the working electrode, a reference electrode and an auxiliary electrode are coplanar, so that the miniaturized design of the electrode spacing of 1-100 mu m is realized, the solution resistance is greatly reduced, the detection responsiveness is improved, the bismuth film modified electrode is applied to heavy metal detection, an alginic acid adhesive film can be modified on the surface of the bismuth film, the electrode performance is further improved, the aim of quickly, conveniently and detecting heavy metals is fulfilled, and a new thought is provided for the design and application of a high-reliability micro sensor.)

1. A bismuth film modified electrode takes a metal electrode as a substrate and comprises a working electrode, a reference electrode and an auxiliary electrode.

2. The bismuth membrane modified electrode as claimed in claim 1, wherein the auxiliary electrode is surface modified with a platinum layer or a carbon slurry modified layer, and the reference electrode is surface modified with silver-silver chloride or porous silver-silver chloride.

3. The bismuth film modified electrode according to claim 1, wherein the distance between the working electrode and the auxiliary electrode is 1-100 μm.

4. The bismuth film modified electrode as claimed in claim 1, wherein the electrode substrate of the bismuth film modified electrode sequentially comprises a conductive inner layer, a conductive outer layer and a reaction layer from bottom to top, the conductive inner layer comprises a Cu layer and a Ni layer, the reaction outer layer is a gold layer, the reaction layer is a bismuth film modified layer, the thickness of the Cu layer is larger than or equal to 15.0 μm, the thickness of the Ni layer is larger than 3.0 μm, the thickness of the gold layer is larger than or equal to 1.2 μm, and the thickness of the bismuth film modified layer is larger than or equal to 5.0 μm.

5. The preparation method of the bismuth film modified electrode as claimed in claim 1, which comprises the following steps:

s1, preparation of a bismuth film: modifying a bismuth film on the surface of the working electrode by adopting an electrochemical method;

s2, preparation of a Pt layer: modifying a metal Pt layer on the surface of the auxiliary electrode by adopting an electrochemical method;

s3, preparation of Ag/AgCl layer: and modifying the surface of the reference electrode with an Ag/AgCl layer by adopting an electrochemical method.

6. The method for preparing the bismuth film modified electrode according to claim 5, wherein in the step S1, the working electrode is pretreated, and then the bismuth film is prepared, specifically: immersing the working electrode into a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature to be 50-60 ℃, the stirring speed to be 150-300 rpm, and the stirring speed to be 1.4-1.6A/dm²Depositing for 180-240 s at the current density, washing with deionized water, and drying.

7. The method for preparing the bismuth film modified electrode according to claim 6, wherein the bismuth plating solution specifically comprises the following components: 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid are dissolved in 80mL of deionized water, 10mL of glycerol solution is added, then concentrated nitric acid is added dropwise under stirring until the solution is dissolved, and finally the total volume of the solution is diluted to 100 mL.

8. The method for preparing the bismuth film modified electrode according to claim 5, wherein the surface of the bismuth film can be modified with an alginate film, and the specific method comprises the following steps: adding 1g of sodium alginate into 100mL of deionized water, stirring for 1h at the stirring speed of 500rpm to obtain a sodium alginate solution, placing the electrode modified with the bismuth film into the sodium alginate solution, soaking for 30s, slowly lifting the electrode out of the solution, soaking the electrode into a 0.1M HCl solution for 15-20 s, and taking out the electrode to remove residual liquid on the surface.

9. The use of the bismuth film modified electrode of claim 1 in the detection of heavy metal ions such as zinc, lead, cadmium, cobalt, chromium, copper, nickel and molybdenum.

10. The use of the bismuth membrane modified electrode in heavy metal ion detection according to claim 9, wherein the bismuth membrane modified electrode can be used for real-time rapid detection of trace heavy metal ions in liquids, including water, sweat, urine and blood.

Technical Field

The invention belongs to the field of electrochemical detection, and particularly relates to a bismuth film modified electrode for heavy metal detection and a preparation method thereof.

Background

Heavy metal means a density of 4.5g/cm³The above metal elements. At present, the current situation of heavy metal pollution in China is very serious, and the heavy metal pollution mainly comprises copper, zinc, arsenic, mercury, lead and the like. The main pollution is water pollution and soil pollution. The heavy metal yield of the industrial wastewater is 24300 tons, the yield of grains polluted by heavy metal reaches 12 million tons every year, and the direct economic loss exceeds 200 million yuan. Any one of these heavy metals can cause headache, dizziness, insomnia, amnesia, nerve disorder, arthralgia, calculus, and cancer (such as hepatocarcinoma, gastric cancer, intestinal cancer, bladder cancer, breast cancer, prostatic cancer, foot and foot diseases and malformation).

With the rapid development of industry and agriculture, the pollution of heavy metals to the natural environment is increasing day by day. Heavy metals are mainly from industries such as pesticide, ceramics, ore mining, smelting and the like. With the discharge of wastewater, even if the concentration of heavy metal ions is in trace and trace levels, the heavy metal ions have the opportunity to gradually accumulate in plants and water sediments in water, the layer-by-layer accumulation through a food chain threatens human bodies, and common heavy metals such as copper, cadmium and lead are marked as environmental priority control pollutants. Therefore, detection of heavy metals is of great importance.

Generally recognized methods for analyzing heavy metals include ultraviolet spectrophotometry (UV), Atomic Absorption Spectroscopy (AAS), Atomic Fluorescence Spectroscopy (AFS), Inductively Coupled Plasma (ICP), X-ray fluorescence spectroscopy (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and the like. The traditional detection methods have the disadvantages of large investment, high cost, difficult carrying and low reaction speed, and cannot meet the requirement of immediate and rapid detection of polluted sites.

The electrochemical anode dissolution method has high detection speed and accurate numerical value, and can be used for emergency detection of environments such as a field and the like, so that the electrochemical sensor is widely concerned. To date, electrochemical sensors have experienced a progression from the pursuit of high sensitivity to highly integrated portable detection. While analyte electrochemical sensors have undergone evolutionary development, they are free of the disadvantages of being difficult to manufacture, difficult to apply, and having poor stability and repeatability. Meanwhile, the designed electrochemical sensor cannot be integrated on an integrated sensor of a microchip due to the complex preparation process of the electrochemical sensor. Based on the above factors, micro-integrated electrochemical sensors have received great attention.

Therefore, the electrochemical method is adopted, the three electrodes are subjected to coplanar design, and the bismuth film with high catalytic activity is used as a catalytic material, so that the sensor has high sensitivity, high stability and low cost, can be matched with a small handheld instrument and an electrochemical workstation for use, realizes low integration sensitivity of the sensing electrode, and promotes the application of the miniature portable sensing electrode in the aspect of heavy metal detection.

Disclosure of Invention

In view of this, the invention provides a bismuth film modified electrode for heavy metal detection and a preparation method thereof.

The invention aims to provide a bismuth film modified electrode, which takes a metal electrode as a substrate and comprises a working electrode and a reference electrode which are not auxiliary electrodes, wherein the working electrode, the reference electrode and the auxiliary electrodes are integrated on the same plane of the metal electrode, and a bismuth film modified layer is modified on the surface of the working electrode.

The surface of the auxiliary electrode is modified with a platinum layer and a carbon slurry modification layer, and the surface of the reference electrode is modified with silver-silver chloride ring porous silver-silver chloride.

The distance between the working electrode and the auxiliary electrode is 1-100 μm.

The electrode substrate of the bismuth film modified electrode sequentially comprises a conductive inner layer, a conductive outer layer and a reaction layer from bottom to top, wherein the conductive inner layer comprises a Cu layer and a Ni layer, the reaction outer layer is a gold layer, the reaction layer is a bismuth film modified layer, the thickness of the Cu layer is more than or equal to 15.0 mu m, the thickness of the Ni layer is more than 3.0 mu m, the thickness of the gold layer is more than or equal to 1.2 mu m, and the thickness of the bismuth film modified layer is more than or equal to 5.0 mu m.

As shown in fig. 1, is a schematic diagram of the bismuth film modified electrode of the present invention. As can be seen from the figure, the bismuth film modified electrode is used as a Working Electrode (WE), an auxiliary electrode (CE) and a Reference Electrode (RE) are integrated on the same plane, wherein the distance between the working electrode and the auxiliary electrode is 1 mu m, the size of the coplanar electrode of the three electrodes is not consistent with that of a USB interface, and the coplanar electrode can not be connected with an electrochemical workstation of any model for use. Through the planar integrated electrode structure, the distance between the electrodes can be greatly reduced, and the sensitivity of the electrode to heavy metal ions is greatly improved.

The composite electrode provided by the invention adopts a standard electrode which conforms to the size of a USB interface as a substrate, one auxiliary electrode is respectively used as a working electrode and an auxiliary electrode, and the other electrode integrated on the same plane is used as a reference electrode, wherein the working electrode is a bismuth film modified electrode, the surface of the auxiliary electrode is modified with platinum, and the surface of the reference electrode is modified with silver-silver chloride. Meanwhile, the working electrode and the reference electrode are not coplanar with each other, the miniaturized design with the electrode spacing of 1-100 mu m is realized, meanwhile, the frequent electrochemical working stations can be directly connected for use, the method is simple, convenient and quick, and the detection time and the step cost are greatly saved.

The bismuth film modified electrode adopts a three-electrode coplanar system, the distance between fixed electrodes is small, concentration polarization in electrochemical test can be obviously eliminated, and the accuracy and the sensitivity of the electrode are effectively improved.

The electrode substrate can be made of epoxy resin ceramic ring PI ring PET ring BT ring metal, and different electrode substrates can be selected according to the detection environment.

The invention also aims to provide a preparation method of the bismuth film modified electrode, which comprises the following steps:

s1, preparation of a bismuth film: modifying a bismuth film on the surface of the working electrode by adopting an electrochemical method;

s2, preparation of a Pt layer: modifying a metal Pt layer on the surface of an auxiliary electrode by adopting an electrochemical method, which specifically comprises the following steps: preparing 1-5 mM H₂PtCl₆And 0.1-0.5M KCl electro-deposition platinum solution, taking a platinum sheet electrode as an electrode, taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.1-0.5V, and carrying out electro-deposition for 10-20 min at normal temperature to obtain a Pt electrode;

s3, preparation of Ag/AgCl layer: modifying an Ag/AgCl layer on the surface of a reference electrode by adopting an electrochemical method, which specifically comprises the following steps: preparing silver plating solution, wherein the specific composition is 40-45 g/L silver nitrate, 200-250 g/L sodium thiosulfate, 40-45 g/L potassium metabisulfite, 20-30 g/L ammonium acetate and 0.6-0.8 g/L thiosemicarbazide; with platinum sheetThe electrode is an auxiliary electrode, the saturated calomel electrode is a reference electrode, and the set current density is 0.2-0.6A/dm²And carrying out electrodeposition for 10-20 min, placing the silver-plated electrode in 0.1-0.5M KCl + 0.01-0.05M HCl solution, taking a platinum sheet electrode as an auxiliary electrode and a commercial Ag/AgCl electrode as a reference electrode, and carrying out cyclic voltammetry scanning at a sweep rate of 30-60 mV/s in a range of-0.15-1.05V to obtain the Ag/AgCl electrode.

Further, in step S1, the pre-processing of the working electrode includes the following steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, tightly bonding the back of the working electrode, and reserving an electrodeposition area of 0.13-0.15 cm on the front of the working electrode²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Further, in step S1, the preparation method of the bismuth film specifically includes: immersing a working electrode into a bismuth plating solution, setting a cathode as a copper plate and an anode as a platinum net, setting the electrodeposition temperature to be 50-60 ℃, the stirring speed to be 150-300 rpm, and the stirring speed to be 1.4-1.6A/dm²Depositing for 180-240 s at the current density, washing with deionized water, and drying.

The bismuth plating solution comprises the following specific components: 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid are dissolved in 80mL of deionized water, 10mL of glycerol solution is added, then concentrated nitric acid is added dropwise under stirring until the solution is dissolved, and finally the total volume of the solution is diluted to 100 mL.

And finally obtaining the three-electrode coplanar composite bismuth membrane electrode Bi @ Ag/AgCl @ Pt by adopting an electrochemical method.

The surface of the bismuth film can be modified with alginic acid glue film, and the specific method comprises the following steps: adding 1g of sodium alginate into 100mL of deionized water, stirring for 1h at the stirring speed of 500rpm to obtain a sodium alginate solution, placing the electrode modified with the bismuth film into the sodium alginate solution, soaking for 30s, slowly lifting the electrode out of the solution, soaking the electrode in 0.1M HCl solution for 15-20 s, taking out the electrode, and removing the residual liquid on the surface of the electrode to obtain the bismuth film modified electrode modified with the alginate film.

Scanning and observing the morphology of the bismuth film modified electrode prepared by the invention by adopting an SEM electron microscope.

As shown in fig. 2, is an SEM topography of the bismuth film modified electrode prepared by the present invention. As can be seen from the figure, the modified bismuth film of the bismuth film modified electrode is a thin film with uniform and compact surface, and the sensitivity and accuracy of the electrode are ensured.

As shown in fig. 3, the SEM morphology of (a) Pt modified layer and (b) Ag/AgCl modified layer prepared by the present invention is shown. As can be seen from fig. 3(a), Pt nanoparticles are distributed relatively uniformly on the substrate surface. The small-size Pt nano particles increase the specific surface area of the Pt auxiliary electrode, so that the Pt auxiliary electrode can be fully contacted with the electrolyte; as can be seen from fig. 3(b), the Ag/AgCl modification layer is composed of continuous pores and ligaments, and this nanostructure greatly increases the speed of ion transport and electron transfer during the redox reaction, and shortens the material transport distance between the electrode/electrolyte interface.

The invention also aims to provide application of the bismuth film modified electrode.

The bismuth membrane modified electrode can be applied to detection of heavy metal ions such as zinc, lead, cadmium, cobalt, chromium, copper, nickel and molybdenum ions, and can be particularly used for real-time rapid detection of trace heavy metal ions in liquid, wherein the liquid comprises water, sweat, urine and blood.

The response performance of the bismuth film modified electrode prepared by the method to different heavy metal ions is tested by adopting a square wave stripping voltammetry method, a cyclic voltammetry scanning method and the like.

As shown in attached figure 4, the bismuth film modified electrode prepared by the invention can be used for detecting heavy metal ions Zn²⁺And (b) a current-concentration fitted graph. As can be seen from the figure, with the heavy metal ion Zn²⁺Is increased in concentration, characterized by a gradually increased peak current, current density and Zn²⁺The ion mass concentration presents a good linear relation, and the linear relation of a fitting curve of the ion mass concentrationThe number is 0.999, which indicates that the bismuth film modified electrode prepared by the invention is applied to heavy metal ions Zn²⁺Has good response performance.

As shown in attached figure 5, the bismuth membrane modified electrode prepared by the invention can be used for detecting heavy metal ions Pb²⁺And (b) a current-concentration fitted graph. As can be seen from the figure, with the heavy metal ion Pb²⁺The concentration of (2) is increased, the characteristic peak current is gradually increased, the current density and Pb²⁺The ion mass concentration presents a good linear relation, and the linear relation coefficient of a fitting curve of the ion mass concentration is 0.996, which shows that the bismuth film modified electrode prepared by the method has a good linear relation with the heavy metal ions Pb²⁺Has good response performance.

As shown in attached figure 6, the bismuth film modified electrode prepared by the invention can be used for detecting heavy metal ions Cd²⁺And (b) a current-concentration fitted graph. As can be seen from the figure, with heavy metal ions Cd²⁺Its characteristic peak current is gradually increased, current density and Cd²⁺The ion mass concentration presents a good linear relation, and the linear relation coefficient of a fitting curve of the ion mass concentration is 0.998, which shows that the bismuth film modified electrode prepared by the method has a high effect on heavy metal ions Cd²⁺Has good response performance.

As shown in figure 7, the bismuth film modified electrode prepared by the invention can be used for detecting heavy metal ions Zn with different concentrations²⁺、Pb^{2 +}、Cd²⁺And (b) a current-concentration fit. As can be seen from the figure, with the heavy metal ion Zn²⁺、Pb²⁺、Cd²⁺The concentration is increased, the characteristic peak current is gradually increased, and a fitting curve of the concentration is in a good linear relation, specifically: heavy metal ion Zn²⁺0.960, heavy metal ion Pb²⁺0.976, heavy metal ion Cd²⁺Is 0.973, which shows that the bismuth film modified electrode prepared by the invention is applied to heavy metal ions Zn²⁺、Pb²⁺、Cd²⁺The device has good response performance, can detect the 3 heavy metal ions simultaneously, and has good anti-interference performance.

As shown in figure 8, the sea prepared by the present inventionAlginate glue film-bismuth film modified electrode for detecting heavy metal ions Zn with different concentrations²⁺、Pb²⁺、Cd²⁺And (b) a current-concentration fit. As can be seen from the figure, with the heavy metal ion Zn²⁺、Pb²⁺、Cd²⁺The concentration is increased, the characteristic peak current is gradually increased, and a fitting curve of the concentration is in a good linear relation, specifically: heavy metal ion Zn²⁺0.988, heavy metal ion Pb²⁺0.998, heavy metal ion Cd²⁺0.997, which shows that the bismuth film modified electrode prepared by the invention is applied to heavy metal ions Zn²⁺、Pb²⁺、Cd²⁺The device has good response performance, can detect the 3 heavy metal ions simultaneously, and has good anti-interference performance.

By comparing the figure 7 with the figure 8, the fact that the dissolution peak of the alginate film-bismuth film modified electrode for detecting 3 heavy metals is obviously higher than that of the bismuth film modified electrode can be found, the fitting curve coefficient of the characteristic peak current without ion concentration is also higher, and the fact that the alginate film is modified on the surface of the bismuth film modified electrode can effectively improve the response performance and sensitivity of the electrode.

The invention provides a method for detecting Zn²⁺、Pb²⁺、Cd²⁺3 kinds of heavy metal ion modified electrodes with bismuth film. Specifically, an electrochemical deposition method is adopted, a bismuth film is modified on the surface of an electrode substrate in situ, the prepared bismuth film modified electrode is used as a working electrode, the working electrode and a reference electrode are coplanar without auxiliary electrodes, the miniaturized design that the electrode spacing is 1-100 mu m is realized, the solution resistance is greatly reduced, the detection responsiveness is improved, the bismuth film modified electrode can be applied to heavy metal detection at high cost, an alginic acid adhesive film can be modified on the surface of the bismuth film, the electrode performance is further improved, the purpose of quickly, conveniently and rapidly detecting heavy metals is realized, and a new thought is provided for the design non-application of a high-reliability micro sensor.

The invention has the beneficial effects that:

(1) according to the invention, the working electrode, the auxiliary electrode and the reference electrode are integrated on the surface of the interdigital electrode, so that the solution resistance is greatly reduced, and the bismuth phase with low catalytic activity is synergistic, therefore, the detection sensitivity is greatly improved, and the rapid detection of trace heavy metal pollutants is realized.

(2) According to the invention, the bismuth film modified electrode is used as a working electrode, the reference electrode and the auxiliary electrode are fixedly arranged on the same plane to form a three-electrode system, so that the integrated immobilization and miniaturization of the distance between electrodes are realized, the resistance value of electrolyte between the electrodes is immobilized, the detection interference caused by the concentration change of a detected substance is eliminated, the purposes of improving the detection sensitivity and the detection data precision of the electrodes are realized, a new thought is provided for the design of a miniature electrochemical sensor, and the popularization and application of a high-reliability portable sensor in real-time detection are promoted.

(3) The electrode provided by the invention is simple in preparation process, the method for modifying metal in situ can effectively avoid inactivation of catalytic substances, the process for modifying the alginate glue film on the surface of the bismuth film is simple, the disposable use is facilitated, the accuracy of detection data is ensured, the reliability of the sensing electrode is improved, and meanwhile, the cost is lower, and the method is suitable for industrial application. The electrode has the characteristics of high sensitivity and high stability, can be used without being connected with an electrochemical workstation, and is simple and quick.

Drawings

The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be obtained on the basis of the following drawings without inventive effort.

FIG. 1 is a schematic view of a bismuth film modified electrode of the present invention;

FIG. 2 is an SEM topography of a bismuth film modified electrode prepared by the invention;

FIG. 3 is an SEM topography of (a) a Pt modified layer and (b) an Ag/AgCl modified layer prepared in accordance with the present invention;

FIG. 4 shows that the bismuth film modified electrode prepared by the invention detects heavy metal ions Zn²⁺The square wave stripping voltammogram and (b) a current-concentration fitted graph of (a);

FIG. 5 shows that the bismuth film modified electrode prepared by the invention detects heavy metal ions Pb²⁺The square wave stripping voltammogram and (b) a current-concentration fitted graph of (a);

FIG. 6 shows that the bismuth film modified electrode prepared by the invention can detect heavy metal ions Cd²⁺The square wave stripping voltammogram and (b) a current-concentration fitted graph of (a);

FIG. 7 shows that the bismuth film modified electrode prepared by the invention detects heavy metal ions Zn with different concentrations²⁺、Pb²⁺、Cd²⁺The cyclic voltammogram of (a) and a current-concentration fit of (b);

FIG. 8 shows that the alginate gel film-bismuth film modified electrode prepared by the invention detects heavy metal ions Zn with different concentrations²⁺、Pb²⁺、Cd²⁺And (b) a current-concentration fitted graph.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following detailed description and the accompanying drawings.

The specific embodiment of the invention comprises the following steps:

a bismuth membrane modified electrode is shown in figure 1, and comprises a working electrode, a reference electrode and a non-auxiliary electrode, wherein the working electrode, the reference electrode and the auxiliary electrode are integrated on the same plane of the metal electrode, a bismuth membrane modified layer is modified on the surface of the working electrode, a platinum layer modified on the surface of the auxiliary electrode is a carbon slurry modified layer, and silver-silver chloride rings and porous silver-silver chloride are modified on the surface of the reference electrode.

The distance between the working electrode and the auxiliary electrode is 1-100 μm.

The electrode substrate of the bismuth film modified electrode sequentially comprises a conductive inner layer, a conductive outer layer and a reaction layer from bottom to top, wherein the conductive inner layer comprises a Cu layer and a Ni layer, the reaction outer layer is a gold layer, the reaction layer is a bismuth film modified layer, the thickness of the Cu layer is more than or equal to 15.0 mu m, the thickness of the Ni layer is more than 3.0 mu m, the thickness of the gold layer is more than or equal to 1.2 mu m, and the thickness of the bismuth film modified layer is more than or equal to 5.0 mu m.

The bismuth film modified electrode is used as a working electrode, the non-auxiliary electrode and the reference electrode are integrated on the same plane to obtain the composite electrode with the USB standard size, and the periphery of the integrated detection area of the non-auxiliary electrode and the auxiliary electrode of the bismuth film modified electrode is provided with a raised dam to prevent the overflow of detection solution.

Example 1

Preparing a bismuth film modified electrode:

1. preparation of bismuth film

Taking epoxy resin as an electrode substrate, and carrying out pretreatment, wherein the method comprises the following specific steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, tightly bonding the back surface of the working electrode, and reserving an electrodeposition area on the front surface of the working electrode of 0.136cm²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Dissolving 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid in 80mL of deionized water, adding 10mL of glycerol solution, dropwise adding concentrated nitric acid under a stirring state until the concentrated nitric acid is dissolved, and finally diluting the total volume of the solution to 100mL to obtain the bismuth-plated solution.

Immersing the pretreated electrode in a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature at 50 ℃, the stirring speed at 150rpm and the stirring speed at 1.4A/dm²Depositing for 240s at the current density, washing with deionized water, and drying to obtain a bismuth film modified electrode as a working electrode of the composite electrode, wherein an SEM topography of the electrode is shown in figure 2.

2. Preparation of a Pt layer: 1mM H was prepared₂PtCl₆And 0.1M KCl electrodeposition platinum solution, taking a platinum sheet electrode as an auxiliary electrode, taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.1V, performing electrodeposition for 20min at normal temperature to obtain a Pt modified electrode serving as an auxiliary electrode of the composite electrode, wherein an SEM topography of the electrode is shown in an attached figure 3 (a).

3. Preparation of Ag/AgCl layer: the prepared silver plating solution comprises 40g/L silver nitrate, 200g/L sodium thiosulfate, 40g/L potassium metabisulfite, 20g/L ammonium acetate and 0.6g/L thiosemicarbazide. Platinum sheet electrode is taken as an auxiliaryAn auxiliary electrode, a saturated calomel electrode as a reference electrode, and a current density of 0.2A/dm²Carrying out electrodeposition for 20min to obtain a silver-plated electrode; and then taking out the silver-plated electrode, putting the silver-plated electrode into 0.1KCl +0.01M HCl solution, using the silver-plated electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode and commercial Ag/AgCl as a reference electrode, carrying out cyclic voltammetry scanning within a range of-0.15-1.05V at a sweep rate of 30mV/s to obtain an Ag/AgCl electrode serving as a reference electrode of a composite electrode, wherein an SEM topography of the electrode is shown as an attached figure 3 (b).

Example 2

Preparing a bismuth film modified electrode:

1. preparation of bismuth film

Taking aluminum nitride ceramic as an electrode substrate, and carrying out pretreatment, wherein the method comprises the following specific steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, tightly bonding the back surface of the working electrode, and reserving an electrodeposition area of 0.139cm on the front surface²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Dissolving 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid in 80mL of deionized water, adding 10mL of glycerol solution, dropwise adding concentrated nitric acid under a stirring state until the concentrated nitric acid is dissolved, and finally diluting the total volume of the solution to 100mL to obtain the bismuth-plated solution.

Immersing the pretreated electrode into a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature as 55 ℃, the stirring speed as 300rpm and the stirring speed as 1.6A/dm²Depositing for 180s at the current density, washing with deionized water, and drying to obtain the bismuth film modified electrode as the working electrode of the composite electrode.

2. Preparation of a Pt layer: 5mM H was prepared₂PtCl₆And 0.5M KCl electrodeposition platinum solution with platinum sheet electrode as auxiliary electrodeAnd taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.5V, and electrodepositing for 10min at normal temperature to obtain a Pt modified electrode serving as an auxiliary electrode of the composite electrode.

3. Preparation of Ag/AgCl layer: the prepared silver plating solution comprises 45g/L silver nitrate, 250g/L sodium thiosulfate, 45g/L potassium metabisulfite, 30g/L ammonium acetate and 0.8g/L thiosemicarbazide. The platinum sheet electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the current density is 0.6A/dm²Carrying out electrodeposition for 10min to obtain a silver-plated electrode; and then taking out the silver-plated electrode, putting the silver-plated electrode into 0.5KCl +0.05M HCl solution, using the silver-plated electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode and commercial Ag/AgCl as a reference electrode, and carrying out cyclic voltammetry scanning within a range of-0.15-1.05V at a sweep rate of 60mV/s to obtain an Ag/AgCl electrode serving as a reference electrode of the composite electrode.

Example 3

Preparing a bismuth film modified electrode:

1. preparation of bismuth film

Taking a BT plate as an electrode substrate, and carrying out pretreatment, wherein the pretreatment comprises the following specific steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, tightly bonding the back surface of the working electrode, and reserving an electrodeposition area of 0.142cm on the front surface²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Dissolving 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid in 80mL of deionized water, adding 10mL of glycerol solution, dropwise adding concentrated nitric acid under a stirring state until the concentrated nitric acid is dissolved, and finally diluting the total volume of the solution to 100mL to obtain the bismuth-plated solution.

Immersing the pretreated electrode in a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature as 60 ℃, and stirringAt a speed of 200rpm and at 1.5A/dm²Depositing for 200s at the current density, washing with deionized water, and drying to obtain the bismuth film modified electrode as the working electrode of the composite electrode.

2. Preparation of a Pt layer: preparation of 3mM H₂PtCl₆And 0.3M KCl electro-deposition platinum solution, taking a platinum sheet electrode as an auxiliary electrode, taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.3V, and electro-depositing for 15min at normal temperature to obtain a Pt modified electrode serving as the auxiliary electrode of the composite electrode.

3. Preparation of Ag/AgCl layer: the prepared silver plating solution consists of 42g/L silver nitrate, 220g/L sodium thiosulfate, 42g/L potassium metabisulfite, 25g/L ammonium acetate and 0.7g/L thiosemicarbazide. The platinum sheet electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the current density is 0.4A/dm²Carrying out electrodeposition for 15min to obtain a silver-plated electrode; and then taking out the silver-plated electrode, putting the silver-plated electrode into 0.3KCl +0.03M HCl solution, using the silver-plated electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode and commercial Ag/AgCl as a reference electrode, and carrying out cyclic voltammetry scanning within a range of-0.15-1.05V at a sweep rate of 40mV/s to obtain an Ag/AgCl electrode serving as a reference electrode of the composite electrode.

Example 4

Preparing a bismuth film modified electrode:

1. preparation of bismuth film

Taking a copper sheet as an electrode substrate, and carrying out pretreatment, wherein the pretreatment comprises the following specific steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, wherein the back surface is tightly adhered, and the front surface is reserved with an electrodeposition area of 0.145cm²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Dissolving 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid in 80mL of deionized water, adding 10mL of glycerol solution, dropwise adding concentrated nitric acid under a stirring state until the concentrated nitric acid is dissolved, and finally diluting the total volume of the solution to 100mL to obtain the bismuth-plated solution.

Immersing the pretreated electrode into a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature at 60 ℃, the stirring speed at 180rpm and the stirring speed at 1.4A/dm²Depositing for 240s under the current density, washing with deionized water, and drying to obtain the bismuth film modified electrode serving as a working electrode of the composite electrode.

2. Preparation of a Pt layer: preparation of 4mM H₂PtCl₆And 0.4M KCl electro-deposition platinum solution, taking a platinum sheet electrode as an auxiliary electrode, taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.2V, and electro-depositing for 10min at normal temperature to obtain a Pt modified electrode serving as the auxiliary electrode of the composite electrode.

3. Preparation of Ag/AgCl layer: the prepared silver plating solution comprises 40g/L silver nitrate, 220g/L sodium thiosulfate, 45g/L potassium metabisulfite, 25g/L ammonium acetate and 0.5g/L thiosemicarbazide. The platinum sheet electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the current density is 0.8A/dm²Carrying out electrodeposition for 8min to obtain a silver-plated electrode; and then taking out the silver-plated electrode, putting the silver-plated electrode into 0.2KCl +0.02M HCl solution, using the silver-plated electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode and commercial Ag/AgCl as a reference electrode, and performing cyclic voltammetry scanning within a range of-0.15-1.05V at a sweep rate of 20mV/s to obtain an Ag/AgCl electrode serving as a reference electrode of the composite electrode.

Example 5

Preparing an alginic acid glue film-bismuth film modified electrode:

1. preparation of bismuth film

Taking epoxy resin as an electrode substrate, and carrying out pretreatment, wherein the method comprises the following specific steps:

(1) oil removal: putting the working electrode into ethanol for ultrasonic oil removal treatment for 30 min;

(2) sealing glue: carrying out mask packaging on the working electrode obtained in the step (1) by using a polytetrafluoroethylene adhesive tape, tightly bonding the back surface of the working electrode, and reserving an electrodeposition area on the front surface of the working electrode of 0.136cm²；

(3) Derusting: soaking the working electrode obtained in the step (2) in sulfuric acid for 30-60 s until the surface is bright;

(4) washing with water: and (4) putting the working electrode obtained in the step (3) into deionized water to remove sulfuric acid.

Dissolving 0.002mol of bismuth nitrate pentahydrate, 0.115mol of potassium nitrate and 0.033mol of tartaric acid in 80mL of deionized water, adding 10mL of glycerol solution, dropwise adding concentrated nitric acid under a stirring state until the concentrated nitric acid is dissolved, and finally diluting the total volume of the solution to 100mL to obtain the bismuth-plated solution.

Immersing the pretreated electrode in a bismuth plating solution, setting the cathode as a copper plate and the anode as a platinum net, setting the electrodeposition temperature at 50 ℃, the stirring speed at 150rpm and the stirring speed at 1.4A/dm²Depositing for 240s under the current density, washing with deionized water, and drying to obtain the bismuth film modified electrode serving as a working electrode of the composite electrode.

2. Preparation of a Pt layer: 1mM H was prepared₂PtCl₆And 0.1M KCl electro-deposition platinum solution, taking a platinum sheet electrode as an auxiliary electrode, taking a commercial Ag/AgCl electrode as a reference electrode, controlling the potential to be-0.1V, and electro-depositing for 20min at normal temperature to obtain a Pt modified electrode serving as the auxiliary electrode of the composite electrode.

3. Preparation of Ag/AgCl layer: the prepared silver plating solution comprises 40g/L silver nitrate, 200g/L sodium thiosulfate, 40g/L potassium metabisulfite, 20g/L ammonium acetate and 0.6g/L thiosemicarbazide. The platinum sheet electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the current density is 0.2A/dm²Carrying out electrodeposition for 20min to obtain a silver-plated electrode; and then taking out the silver-plated electrode, putting the silver-plated electrode into 0.1KCl +0.01M HCl solution, using the silver-plated electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode and commercial Ag/AgCl as a reference electrode, and carrying out cyclic voltammetry scanning within a range of-0.15-1.05V at a sweep rate of 30mV/s to obtain an Ag/AgCl electrode serving as a reference electrode of the composite electrode.

4. Modification of an alginate gel film: adding 1g of sodium alginate into 100mL of deionized water, stirring for 1h at the stirring speed of 500rpm to obtain a sodium alginate solution, placing the electrode modified with the bismuth film into the sodium alginate solution, soaking for 30s, slowly lifting the electrode out of the solution, soaking the electrode into a 0.1M HCl solution for 20s, taking out the electrode, and removing the residual liquid on the surface of the electrode to obtain the bismuth film modified electrode modified with the alginic acid film.

Example 6

Detection of heavy metal ions Zn by bismuth film modified electrode²⁺And (6) carrying out testing.

Using the bismuth film modified electrode prepared in example 1 as a working electrode, a platinum electrode as an auxiliary electrode and a silver-silver chloride modified electrode as a reference electrode, placing the three-electrode system in an acetic acid-sodium acetate (pH 6.0) buffer solution, and adding Zn with a certain concentration in advance²⁺Performing electrodeposition treatment on the ionic solution, standing, and sequentially adding Zn of 40. mu.g/L, 80. mu.g/L, 120. mu.g/L, 160. mu.g/L, 200. mu.g/L, 240. mu.g/L and 280. mu.g/L²⁺Setting the deposition potential to-1.4V, the deposition time to 30s and the scanning potential to-1.4-0.4V for the ionic solution, performing square wave stripping voltammetry, and setting the incremental potential to 0.004V to obtain the attached figure 4.

Example 7

Heavy metal ion Pb detection for bismuth film modified electrode²⁺And (6) carrying out testing.

Using the bismuth film modified electrode prepared in example 1 as a working electrode, a platinum electrode as an auxiliary electrode and a silver-silver chloride modified electrode as a reference electrode, placing the three-electrode system in an acetic acid-sodium acetate (pH 5.0) buffer solution, and adding a certain concentration of Pb in advance²⁺Performing electrodeposition treatment on the ionic solution, standing, and sequentially adding 1. mu.g/L, 2. mu.g/L, 3. mu.g/L, 4. mu.g/L, 5. mu.g/L, 6. mu.g/L, 7. mu.g/L and 8. mu.g/L of Pb²⁺Setting the deposition potential to-1.2V, the deposition time to 180s and the scanning potential to-1.0-0.4V for the ionic solution, performing square wave stripping voltammetry, and setting the incremental potential to 0.004V to obtain the attached figure 5.

Example 8

Heavy metal ion Cd detection for bismuth film modified electrode²⁺And (6) carrying out testing.

Using the bismuth film modified electrode prepared in example 1 as a working electrode, a platinum electrode as an auxiliary electrode, and a silver-silver chloride modified electrode as a reference electrode, the three-electrode system was placed in 0.1M PBS (pH 7.0) buffer solution, and Cd of a certain concentration was added in advance²⁺Electrodeposition from ionic solutionsTreating, standing, and sequentially adding Cd of 5. mu.g/L, 6. mu.g/L, 7. mu.g/L, 8. mu.g/L, 9. mu.g/L, 10. mu.g/L, 11. mu.g/L, 12. mu.g/L, 13. mu.g/L, 14. mu.g/L and 15. mu.g/L²⁺Setting the deposition potential to-1.2V, the deposition time to 180s and the scanning potential to-1.0-0.4V for the ionic solution, performing square wave stripping voltammetry, and setting the incremental potential to 0.004V to obtain the attached figure 6.

Example 9

Simultaneous detection of Zn on bismuth film modified electrode²⁺、Pb²⁺、Cd²⁺Three heavy metal ions were tested.

Using the bismuth film modified electrode prepared in example 1 as a working electrode, a platinum electrode as an auxiliary electrode and a silver-silver chloride modified electrode as a reference electrode, and preparing Zn with the same concentration²⁺、Pb²⁺、Cd²⁺Adding heavy metal ion supplementing solution, adding the three-electrode system into acetic acid-sodium acetate (pH 4.5) buffer solution, and slowly adding Zn²⁺、Pb²⁺、Cd²⁺And (3) adding a heavy metal ion supplement liquid, performing cyclic voltammetry detection and recording data when the concentrations of 3 heavy metal ions are 40mg/L, 60mg/L, 80mg/L, 100mg/L, 120mg/L and 140mg/L, setting the scanning speed to be 50mV/s and the scanning potential to be-1.4 to-0.4V, and obtaining the attached figure 7.

Example 10

Simultaneously detecting Zn by using alginate glue film-bismuth film modified electrode²⁺、Pb²⁺、Cd²⁺Three heavy metal ions were tested.

Using the alginate gel film-bismuth film modified electrode prepared in example 5 as a working electrode, a platinum electrode as an auxiliary electrode and a silver-silver chloride modified electrode as a reference electrode, and preparing Zn with the same concentration²⁺、Pb²⁺、Cd²⁺Adding heavy metal ion supplementing liquid, placing the three-electrode system in 0.1M acetic acid-sodium acetate (pH 6.0) buffer solution, magnetically stirring while depositing at-1.4V, standing for 20s after 180s deposition, dissolving under-1.4-0.4V, and slowly adding Zn²⁺、Pb²⁺、Cd²⁺The heavy metal ion supplementing liquid has the concentration of 3 heavy metal ions of 100 mug/L, 200 mug/L, 300 mug/L, 400 mug/L and 500 mugAnd performing square wave stripping voltammetry test and data recording during the/L period, and setting the incremental potential to be 0.004V to obtain the attached figure 8.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, each embodiment may include only a single technical solution, and such description of the description is for clarity only, and those skilled in the art should take the description as a whole, and the technical solutions in the embodiments may be combined appropriately to form other embodiments that may be understood by those skilled in the art. The technical details not described in detail in the present invention can be implemented by any of the prior arts in the field. In particular, all technical features of the invention which are not described in detail can be achieved by any prior art.